Authors:Richard Hatley; Simon Macdonald, Robert Slack, Joelle Le, Steve Ludbrook, Pauline LukeyAbstract: There is a requirement for efficacious and safe medicines to treat diseases with high unmet need. The resurgence in av RGD integrin inhibitor drug discovery is poised to contribute to this requirement. However, drug discovery in the av integrin space is notoriously difficult due to the receptors being structurally very similar as well as the polar zwitterionic nature of the pharmacophore. This review aims to guide drug discovery research in this field through an av inhibitor toolbox, consisting of small molecules and antibodies. Small molecule av tool compounds with extended profiles in avb1, 3, 5, 6 and 8 cell adhesion assays, with key physicochemical properties, have been collated to assist in the selection of the right tool for the right experiment. This should also facilitate an understanding of partial selectivity profiles of compounds generated in different assays across research institutions. Prospects for further av integrin research and the critical importance of target validation are discussed, where increased knowledge of the selectivity for individual RGD v integrins is key. Insights into the design of small molecule RGD chemotypes for topical or oral administration are provided and clinical findings on advanced molecules are examined.PubDate: 2017-09-25T03:21:33.857824-05:DOI: 10.1002/ange.201707948

Authors:Shenghua Liu; Shenghuang Lin, Peng You, Charles Surya, Daniel Lau, Feng YanAbstract: Although organic photovoltaic devices (OPVs) have been investigated for more than two decades, the power conversion efficiencies of OPVs are much lower than those of inorganic or perovskite solar cells. One effective approach to improve the efficiency of OPVs is to introduce additives to enhance light harvesting as well as charge transportation in the devices. Here, black phosphorus quantum dots (BPQDs) are introduced in OPVs as an additive. By adding 0.055 wt % BPQDs relative to the polymer donors in the OPVs, the device efficiencies can be dramatically improved for more than 10 %. The weight percentage is much lower than that of any other additive used in OPVs before, which is mainly due to the two-dimentional structure as well as the strong broadband light absorption and scattering of the BPQDs. This work paves a way for using two-dimentional quantum dots in OPVs as a cost-effective approach to enhance device efficiencies.Starke Lichtabsorption: Die Wirkungsgrade organischer Photovoltaikeinheiten wurden durch Einführung von Quantenpunkten aus schwarzem Phosphor (BPQDs; 0.055 Gew.-% relativ zu den Donorpolymeren) verbessert. Der Effekt wird der starken Lichtabsorption und der zweidimensionalen Struktur der BPQDs zugeschrieben. Ein ausgeprägter Größeneffekt der BPQDs auf die Leistungssteigerung wird beobachtet.PubDate: 2017-09-25T01:51:02.27211-05:0DOI: 10.1002/ange.201707510

Authors:Nema Hafezi; Wondimagegn T Shewa, James C Fettinger, Mark MascalAbstract: A new concept in anionic 10 pi aromaticity is described by the embedding of a compensating charge within an aromatic cyclononatetraenide ring by the symmetric interposition of a methylammonium bridge. This is accomplished by the alkylation of azatriquinacene to give a quaternary ammonium salt, followed by oxidation to the tetraene and final deprotonation. The resulting zwitterion is a stable [9]annulene with strong aromaticity as shown by its degree of C-C bond equalization and a nucleus independent chemical shift value lower than that of benzene. The solid-state structure shows an eclipsed stacking motif with the electron poor ammonium methyl groups occupying the electron rich cavity of the aromatic bowl.PubDate: 2017-09-24T21:20:57.224261-05:DOI: 10.1002/ange.201708521

Authors:Xinrong Zhang; Jinyu Wang, Jie Xue, Zihe Yan, Sichun Zhang, Juan QiaoAbstract: Designing probes for real-time imaging of dynamic processes in living cells is a continual challenge. Herein, a novel near-infrared photoluminescence probe with long lifetime was exploited for photoluminescence lifetime imaging (PLIM) based on an Iridium-alkyne complex. This probe offers benefits of desirable deep-red to NIR emission, long stokes shift, excellent cell penetration, low cytotoxicity and good resistance to photobleaching. To the best of our knowledge this is the first PLIM probe applicable to click reaction of Cu(I)-catalysed azide-alkyne cycloaddition with remarkable lifetime shifts of 414 ns before and after click reaction. The approach fully eliminates the background interference and well distinguishes the reacted probes from the unreacted probes, thus enabling the wash-free imaging of the newly synthesized proteins in single living cells. Based on the unique properties of the Iridium complexes, it is anticipated to be applied in more important issues in living cells.PubDate: 2017-09-23T06:21:04.652052-05:DOI: 10.1002/ange.201708566

Authors:Rein V Ulijn; Chunqiu Zhang, Ramim Shafi, Ayala Lampel, Douglas MacPherson, Charalampas Pappas, Vishal Narang, Tong Wang, Charles MadarelliAbstract: The reversible regulation of catalytic activity is a feature found in natural enzymes which is not commonly observed in artificial catalytic systems. Here, we fabricate an artificial hydrolase with pH-switchable activity, achieved by introducing a catalytic histidine residue at the terminus of a pH-responsive peptide. The peptide exhibits a conformational transition from random coil to β-sheet by changing the pH from acidic to alkaline. The β-sheet self-assembles to form long fibrils with the hydrophobic edge and histidine residues extending in an ordered array as the catalytic microenvironment, which shows significant esterase activity. Catalytic activity can be reversible switched by pH-induced assembly/ disassembles of the fibrils into random coils. At higher concentrations, the peptide forms a hydrogel which is also catalytically active and maintains its reversible (de-)activation.PubDate: 2017-09-22T23:25:50.281099-05:DOI: 10.1002/ange.201708036

Authors:Nicholas Robert Vance; Michael Ashley Spies, Lokesh GakharAbstract: The caspase family of cysteine proteases are highly sought after drug targets due to their essential roles in apoptosis, proliferation and inflammation pathways. High throughput screening efforts to discover inhibitors have gained little traction. Fragment-based screening has emerged as a powerful tool for the discovery of innovative drug leads. This methodology has become a central facet of drug discovery campaigns in the pharmaceutical industry and academia. A fragment-based drug discovery campaign against human caspase-7 resulted in the discovery of a novel series of allosteric inhibitors. An X-ray crystal structure of caspase-7 bound to a fragment hit, and a thorough kinetic characterization of a zymogenic form of the enzyme are used to investigate the allosteric mechanism of inhibition. This work further advances our understanding of the mechanisms of allosteric control of this class of pharmaceutically relevant enzymes, and provides a new path forward for drug discovery efforts.PubDate: 2017-09-22T23:25:25.37387-05:0DOI: 10.1002/ange.201706959

Authors:Sabine Flitsch; Alexander Wood, Nicholas Weise, Joseph Frampton, Mark Dunstan, Michael Hollas, Sasha Derrington, Richard LLoyd, Daniela Quaglia, Fabio Parmeggiani, David Leys, Nicholas TurnerAbstract: Carboxylic acid reductases (CARs) catalyze the reduction of a broad range of carboxylic acids to aldehydes using the co-factors ATP and NADPH, and have become attractive biocatalysts for organic synthesis. Here we exploit our mechanistic understanding of CARs to expand their reaction scope, generating biocatalysts for amide bond formation from carboxylic acid and amine. After reaction engineering, CARs were found to have amidation activity for various acids and amines. Optimization of reaction conditions with respect to pH and temperature allowed for the synthesis of the anticonvulsant ilepcimide with up to 96% conversion. Mechanistic studies using site-directed mutagenesis suggest that following initial enzymatic adenylation of substrates, amidation of the carboxylic acid proceeds via direct reaction of the acyl adenylate with amine nucleophiles.PubDate: 2017-09-22T15:25:52.837202-05:DOI: 10.1002/ange.201707918

Authors:Thomas Friedrich Fässler; Kerstin Mayer, Jasmin Dums, Wilhelm KleinAbstract: The new [SnBi3]5- polyanion is obtained by the reaction of K3Bi2 with K4Sn9 or K12Sn17 in liquid ammonia. The anion is iso(valence)electronic with and structurally analogous to the carbonate ion. Despite the high negative charge of the anion, the Sn-Bi bond lengths range between single and double bonds. Quantum-chemical calculations at a DFT-PBE0/def2-TZVPP/COSMO level of theory reveal that the partial double bond character between the heavy main group atoms Bi and Sn originates from a delocalized π-electronic system. The structure of the anion is determined by single crystal X-ray diffraction analyses of the compounds K5[SnBi3](NH3)9 (1) and K9[K(18-crown-6)][SnBi3]2(NH3)15 (2). The [SnBi3]5- unit is the first example of a carbonate-like anion obtained from solution, and it consists exclusively of metal atoms.PubDate: 2017-09-22T14:20:22.759405-05:DOI: 10.1002/ange.201709700

Authors:Qinfeng Rong; Wenwei Lei, Lie Chen, Yongai Yin, Jiajia Zhou, Mingjie LiuAbstract: Conductive hydrogels emerge as a fascinating class of stretchable conductive materials that are important for various applications. However, water-based conductive hydrogels inevitably lose elasticity and conductivity at subzero temperatures, which severely limits their practical applications at low temperatures. Here we report anti-freezing conductive organohydrogels by using an H2O/ethylene glycol binary solvent as dispersion medium. Owing to the freezing tolerance of the binary solvent, our organohydrogels exhibit stable flexibility and strain-sensitivity in the temperature range from -55.0 to 44.6 °C. Meanwhile, the solvent molecules could form hydrogen bonds with polyvinyl alcohol (PVA) chains and induce the crystallization of PVA, greatly improve the mechanical strength of the organohydrogels. Furthermore, the non-covalent crosslinks endow the conductive organohydrogels with intriguing remoldability and self-healing capability, which are important for practical applications.PubDate: 2017-09-22T11:28:10.285241-05:DOI: 10.1002/ange.201708614

Authors:Wilbert J. Smit; Huib J. BakkerAbstract: The surface of ice has been reported to be disordered at temperatures well below the bulk melting point. However, the precise nature of this disorder has been a topic of intense debate. Here, we study the molecular properties of the surface of ice as a function of temperatures using heterodyne-detected sum-frequency generation spectroscopy. We observe that, down to 245 K, the spectral response of the surface of ice contains a component that is indistinguishable from supercooled liquid water.PubDate: 2017-09-22T08:20:37.140242-05:DOI: 10.1002/ange.201707530

Authors:Daniel T. Chiu; Xu Wu, Quinn Degottardi, I-Che Wu, Jiangbo Yu, Li Wu, Fangmao Ye, Chun-Ting Kuo, William W KwokAbstract: Simultaneous monitoring of biomarkers as well as single-cell analyses based on flow cytometry and mass cytometry are important for investigations of disease mechanisms, drug discovery, and signaling-network studies. Flow cytometry and mass cytometry are complementary to each other; however, probes that can satisfy all the requirements for these two advanced technologies are limited. In this study, we report a probe of lanthanide-coordinated semiconducting polymer dots (Pdots), which possess fluorescence and mass signals. We demonstrated the usage of this dual-functionality probe for both flow cytometry and mass cytometry in a mimetic cell mixture and human peripheral blood mononuclear cells as model systems. The probes not only offer high fluorescence signal for use in flow cytometry, but also show better performance in mass cytometry than the commercially available counterparts.PubDate: 2017-09-22T08:20:27.841838-05:DOI: 10.1002/ange.201708463

Authors:Olivier Dalstein; Effrosyni Gkaniatsou, Clemence Sicard, Ozlem Sel, Hubert Perrot, Christian Serre, Cedric Boissiere, Marco FaustiniAbstract: Herein, a straightforward crack-patterning method is reported allowing the direct formation of periodic cracks in Metal-Organic Framework nanoparticles films during dip-coating deposition. The crack propagation and periodicity can be easily tailored by controlling the evaporation front and the withdrawal speed. Several MOF patterned films can be fabricated on large surfaces and on several substrates (flat, curved or flexible) including the inner surface of a tube, not achievable by other lithographic techniques. We demonstrate that the periodic cracked arrays diffract light and, thanks to the MOF sorption properties, photonic vapor sensors are fabricated. A new concept of "in-tube", MOF-based diffraction grating sensors is proposed with outstanding sensitivity that can be easily tuned "on-demand" as function of the desired detection range.PubDate: 2017-09-22T06:21:07.892252-05:DOI: 10.1002/ange.201706745

Authors:Haixing Li; Timothy Su, María Camarasa-Gómez, Daniel Hernangómez-Pérez, Simon Henn, Vladislav Pokorný, Caravaggio Dante Caniglia, Michael Inkpen, Richard Korytár, Michael Steigerwald, Colin Nuckolls, Ferdinand Evers, Latha VenkataramanAbstract: We report that the single molecule junction conductance of thiol-terminated silanes with Ag electrodes are higher than the conductance of those formed with Au electrodes. These results are in contrast to the trends in the metal work function Φ(Ag) < Φ(Au). As such, one would expect a better alignment of the Au Fermi level to the molecular orbital of silane that mediates charge transport. Additionally, this conductance trend is reversed when we replace the thiols with amines, highlighting the impact of metal—S covalent and metal—NH2 dative bonds in controlling the molecular conductance. Density functional theory calculations elucidate the crucial role of the chemical linkers in determining the level alignment when molecules are attached to different metal contacts. We also demonstrate that conductance of thiol terminated silanes with Pt electrodes is lower than the ones formed with Au and Ag electrodes again in contrast to what one would expect from trends in the metal work-functions.PubDate: 2017-09-22T06:20:20.329067-05:DOI: 10.1002/ange.201708524

Authors:Sandra M. Lang; Thorsten M. Bernhardt, Valeriy Chernyy, Joost M. Bakker, Robert N. Barnett, Uzi LandmanAbstract: Methane represents the major constituent of natural gas. It is primarily used only as a source of energy by means of combustion, but could also serve as an abundant hydrocarbon feedstock for high quality chemicals. One of the major challenges in catalysis research nowadays is therefore the development of materials that selectively cleave one of the four C−H bonds of methane and thus make it amenable for further chemical conversion into valuable compounds. By employing infrared spectroscopy and first-principles calculations it is uncovered herein that the interaction of methane with small gold cluster cations leads to selective C−H bond dissociation and the formation of hydrido methyl complexes, H-Aux+-CH3. The distinctive selectivity offered by these gold clusters originates from a fine interplay between the closed-shell nature of the d states and relativistic effects in gold. Such fine balance in fundamental interactions could prove to be a tunable feature in the rational design of a catalyst.C-H-Spalterei: Schwingungsspektroskopie in Verbindung mit First-Principles-Rechnungen zeigt, dass kleine Goldcluster die selektive Dissoziation einer der vier C-H-Bindungen von Methan vermitteln können – der erste Schritt der CH4-Umwandlung in höherwertige Chemikalien. Die besondere Selektivität der Goldcluster resultiert aus ihrer fein abgestimmten elektronischen Struktur. Au: gelb, C: grau, H: weiß.PubDate: 2017-09-22T06:10:31.202708-05:DOI: 10.1002/ange.201706009

Authors:Qingqing Mei; Huizhen Liu, Xiaojun Shen, Qinglei Meng, Hangyu Liu, Junfeng Xiang, Buxing HanAbstract: Selective transformation of lignin into a valuable chemical is of great importance and challenge owing to its complex structure. Herein, we propose a strategy for the transformation of methoxy group (-OCH3) which is abundant in lignin into pure highly valuable chemicals. As an example to apply this strategy, a route to produce acetic acid with high selectivity by conversion of methoxy group of lignin was developed. It was demonstrated that the methoxy group in lignin could react with CO and water to generate acetic acid over RhCl3 in the presence of a promoter. The conversions of methoxy group in the kraft lignin and organosolv lignin reached 87.5 % and 80.4 %, respectively, and no by-product was generated. This work opens the way to produce pure chemicals using lignin as the feedstock.Die (Bio)Masse macht's: Die Umwandlung von Methoxygruppen aus Lignin in Essigsäure gelingt durch selektive Umsetzung mit CO und Wasser über RhCl3. Bei 100 %iger Selektivität für Essigsäure sind Umsätze bis 87.5 % möglich.PubDate: 2017-09-22T06:10:26.753002-05:DOI: 10.1002/ange.201706846

Authors:Kai Johnsson; Julien Hiblot, Qiluiyang Yu, Marina Sabbadini, Luc Reymond, Lin Xue, Olivier Sallin, Alberto Schena, Rudolf Griss, Nicholas HillAbstract: We introduce luciferases whose emission maxima can be tuned to different wavelengths by chemical labeling. These tunable luciferases are generated by inserting the small luciferase NanoLuc into the structures of the self-labeling proteins SNAP-tag or HaloTag7 near their active sites. Labeling of the tags with a fluorophore shifts the emission maximum of NanoLuc to that of the fluorophore. Luciferases with tunable colors have applications as reporter genes, for the construction of biosensors and in bioimaging.PubDate: 2017-09-22T05:20:36.843492-05:DOI: 10.1002/ange.201708277

Authors:Sarah E. Wood; Gaurav Sinsinbar, Sushanth Gudlur, Madhavan Nallani, Che-Fan Huang, Bo Liedberg, Milan MrksichAbstract: Identifying peptide substrates that are efficiently cleaved by proteases can give insights into the substrate recognition and specificity, guide the development of inhibitors and improve the sensitivity of assays. Peptide arrays and SAMDI mass spectrometry were used to identify a tetrapeptide substrate exhibiting high activity for the bacterial outer membrane protease (OmpT). Analysis of protease activity for the preferred residues at the cleavage site (P1, P1') and nearest neighbor positions (P2, P2') and their positional interdependence revealed FRRV as the optimal peptide with the highest OmpT activity. Substituting FRRV into a fragment of LL37, a natural substrate of OmpT, led to a>400 fold improvement in OmpT's catalytic efficiency with a kcat/Km value of 6.1 x 106 M-1 s-1. Interestingly, wild-type and mutant OmpT displayed significant differences in their substrate specificities, demonstrating that even modest mutants may not be suitable substitutes for the native enzyme.PubDate: 2017-09-22T03:22:12.397002-05:DOI: 10.1002/ange.201707535

Authors:Nicolai Cramer; Yun-Suk Jang, Michael DieckmannAbstract: An enantioselective C-H amidation of phosphine oxides by using an iridium(III) catalyst bearing an atropchiral cyclopentadienyl (Cpx) ligand is reported. A very strong cooperative effect between the chiral Cpx ligand and a phthaloyl tert-leucine enabled the transformation. Matched-mismatched cases of the different acid enantiomers are shown. The amidated P-chiral arylphosphine oxides are formed in yields of up to 95 % and with excellent enantioselectivities of up to 99:1 er. Enantiospecific reduction provides access to valuable P-chiral phosphorus(III) compounds.PubDate: 2017-09-22T03:21:49.953647-05:DOI: 10.1002/ange.201708440

Authors:Jaehoon Jeong; Myounghoon Choun, Jaeyoung LeeAbstract: Metal-free N-doped porous carbon has great potential as a catalyst for hydrazine oxidation in direct hydrazine fuel cells (DHFCs). However, previous studies have reported only half-cell characterization, and the effect of the pore size distribution has not been intensively investigated. Herein, we report the synthesis of highly active, metal-free N-doped carbon (NDC) by controlling the pore size distribution, and for the first time, the effect of the pore size distribution on the anode performance in a DHFC is investigated. As a result, tree-bark-shaped NDC with meso/macroporous (>10 nm) structures exhibit a remarkable power density of 127.5 mW cm−2 in a DHFC.Nano und Natur: N-dotierte poröse Nanofasern mit Baumrinden-artiger Maserung sind hoch aktive metallfreie Katalysatoren für die Hydrazinoxidation in Hydrazin-Brennstoffzellen.PubDate: 2017-09-22T02:47:14.148049-05:DOI: 10.1002/ange.201707880

Authors:Tatsuo KimuraAbstract: The precise control of primary reactions in solutions is one of the most significant steps for the nanoscale design of inorganic solids in multidisciplinary fields. However, further growth of the inorganic species to give bulkier species disturbs such designs. The surfactant-assisted synthesis of mesoporous materials is a good strategy for addressing such concerns because pores formed by supramolecularly mediated processes are surrounded by nanometer-sized continuous frameworks. Many experiments are generally conducted to optimize the reaction conditions for the synthesis of highly ordered mesostructures. Herein, to minimize such trial-and-error efforts, a new and practical concept is proposed for the precise design of porous materials. By adjusting the reactivity between bisphosphonates and metal sources through molecular design of the starting bisphosphonate compound, it was possible to synthesize mesoporous films with unique compositions by a surfactant-assisted approach.Schluss mit Versuch und Irrtum: Normalerweise erfordert die Optimierung der Reaktionsbedingungen zur Synthese hoch geordneter Mesostrukturen viele Experimente. Durch Abstimmung der Reaktivität zwischen Bisphosphonaten und einer Metallquelle mithilfe von molekularem Design des Bisphosphonats war es nun möglich, präzise entworfene mesoporöse Filme mit einzigartiger Zusammensetzung durch einen oberflächenunterstützten Ansatz zu synthetisieren.PubDate: 2017-09-22T02:46:39.127599-05:DOI: 10.1002/ange.201707225

Authors:Tao Gao; Singyuk Hou, Fei Wang, Zhaohui Ma, Xiaogang Li, Kang Xu, Chunsheng WangAbstract: The redox chemistry of magnesium and its application in rechargeable Mg batteries has received increasing attention owing to the unique benefits of Mg metal electrodes, namely high reversibility without dendrite formation, low reduction potentials, and high specific capacities. The Mg/S couple is of particular interest owing to its high energy density and low cost. Previous reports have confirmed the feasibility of a rechargeable Mg/S battery; however, only limited cycling stability was achieved, and the complicated procedure for the preparation of the electrolytes has significantly compromised the benefits of Mg/S chemistry and hindered the development of Mg/S batteries. Herein, we report the development of the first rechargeable Mg/S battery with a MgTFSI2/MgCl2/DME electrolyte (DME=1,2-dimethoxyethane, TFSI=bis(trifluoromethanesulfonyl)imide) and realize the best cycling stability among all reported Mg/S batteries by suppressing polysulfide dissolution. Mechanistic studies show that the battery works via S0/MgSx redox processes and that the large voltage hysteresis is mainly due to the Mg anode overpotential.Die Mischung macht's: Eine MgTFSI2/MgCl2/DME-Mischung (DME=1,2-Dimethoxyethan, TFSI=Bis(trifluormethansulfonyl)imid) wurde als Silylamid-freies, leicht herzustellendes Elektrolyt in Untersuchungen zur S0/MgSx-Redoxchemie eingesetzt. Seine Verwendung in einer Mg/S-Batterie führte zur besten Zyklenstabilität, die bislang für solche Systeme beobachtet wurde, da sich Polysulfide im konzentrierten Elektrolyt (1 m) nicht auflösen.PubDate: 2017-09-22T02:35:29.920512-05:DOI: 10.1002/ange.201708241

Authors:Shibaji Basak; Ishwar Singh, Annaleizle Ferranco, Jebreil Syed, Heinz-Bernhard KraatzAbstract: Homochirality in peptides is crucial in sustaining “like–like” intermolecular interactions that allow the formation of assemblies and aggregates and is ultimately responsible for the resulting material properties. With the help of a series of stereoisomers of the tripeptide F–F–L, we demonstrate the critical role that peptide stereochemistry plays in the self-assembly of peptides, guided by molecular recognition, and for self-sorting. Homochiral self-assemblies are thermally and mechanically more robust compared to heterochiral self-assemblies. Morphological studies of the multicomponent peptide systems showed that aggregates formed from homochiral peptides possessed a uniform nano-fibrous structure, whereas heterochiral systems resulted in self-sorted systems with a heterogeneous morphology. In essence, homochiral peptides form the stronger aggregates, which may be one of reasons why homochirality is preferred in living systems.Reich' mir die Händigkeit, mein Leben: Stereochemie ist ein wichtiger Faktor in der Peptid-Selbstorganisation unter dem steuernden Einfluss von molekularer Erkennung und Selbstsortierung. Homochirale Peptide bilden die stärkeren Aggregate, was ein Grund für die bevorzugte Homochiralität in lebenden Systemen ist.PubDate: 2017-09-22T01:07:06.714104-05:DOI: 10.1002/ange.201706162

Authors:Yi Xu; Jason Riordon, Xiang Cheng, Bo Bao, David SintonAbstract: Knowing the thermodynamic state of complex mixtures - liquid, gas, supercritical or two-phase - is essential to industrial chemical processes. Traditionally, phase diagrams are compiled piecemeal from individual measurements in a pressure-volume-temperature cell performed in series, where each point is subject to a long fluid equilibrium time. Herein, 1,000 microfluidic chambers, each isolated by a liquid piston and set to a different pressure and temperature combination, provide the complete pressure-temperature phase diagram of a hydrocarbon mixture at once, including the thermodynamic phase envelope. Measurements closely match modelled values, with a standard deviation of 0.13 MPa between measurement and model for the dew and bubble point lines, and a difference of 0.04 MPa and 0.25 ºC between measurement and model for the critical point.PubDate: 2017-09-21T12:21:00.704781-05:DOI: 10.1002/ange.201708238

Authors:Thomas Carell; Matthias Q Kurz, Markus Müller, Martin Rossa, Fabio SpadaAbstract: The sequence of the four canonical bases dA, dC, dG and dT forming two defined Watson-Crick base pairs (dT:dA, dG:dC), held together by H-bonding, establish the sequence information in the DNA double strand. The faithful replication of the sequence information during cell division, the transcription of the DNA information into RNA and the final translation of the sequence information into proteins is the basis for life on earth. Multicellular organisms developed the concept of specialized cells that perform specific functions. Examples are neurons and fibroblast to name just two out of more than 200. These cellular differences are established based on the same sequence information stored in the cell nucleus of all cells of an organism. The sequence information needs consequently different interpretations by the different cell types. During cellular development, when a zygote develops finally into a complex organism with its multitude of specialized cells, this interpretation of the genetic code has to be tightly regulated in space and time. Interpretation of the sequence information involves the controlled activation and silencing of specific genes so that certain proteins are made in one cell type but not in others. This involves an additional regulatory information layer beyond the pure base sequence. One aspect of this regulatory information layer relies on functional groups that are attached to the C(5) position of the canonical base dC. Currently four regulatory, non-canonical bases with a methyl (CH3)-, a hydroxymethyl (CH2OH)-, a formyl (CHO)- and a carboxyl (COOH)- group are known. While 5-methyl-cytidine is long recognized to be a regulatory base in the genome, the other three bases and the enzymes responsible for generating them, were just recently discovered. This review summarizes the discovery of the new bases and focusses at the chemical biology aspects associated with the regulatory DNA bases beyond Watson and Crick.PubDate: 2017-09-21T11:20:44.353473-05:DOI: 10.1002/ange.201708228

Authors:Yu-Te Wey; Fan-Shan Yang, Hsien-Chen Yu, Ting-Shen Kuo, Yi-Chou TsaiAbstract: Here we report the preparation of an unprecedented Ge(I)-Ge(I) bonded digermylene [K2{Ge2(μ-κ2:η2:η4-2,6-(2,6-iPr2C6H3-N)2-4-CH3C5H2N)2}] (3) in an eclipsed conformation stabilized by two bridging diamidopyridyl ligands. Although 3 exhibits an eclipsed conformation, the Ge-Ge bond length is 2.5168(6) Å, shorter than those in the trans-bent and gauche digermylenes. In combination with two pendant amido groups, the GeI2 motif of 3 is employed as a building block to assemble the first example of octagermylene [Ge4(μ-κ2:κ1-2,6-(2,6-iPr2C6H3-N)2-4-CH3C5H2N)2]2 (5) showing a cyclic configuration and containing three distinct types of Ge(I)-Ge(I) bonds.PubDate: 2017-09-21T09:21:12.838391-05:DOI: 10.1002/ange.201708551

Authors:Ulrike Kroesen; Christian Unkelbach, Daniel Schildbach, Carsten StrohmannAbstract: In this communication, a selective way and a better understanding to control the reaction of allylic amines with metalorganic bases depending on the amine handle as well as the metalorganic base is presented. Depending on the number of coordinating groups within the amine handle either a selective carbometalation or deprotonation reaction can be performed. By changing the alkali metal within the base from lithium to sodium or potassium, a change of chemoselectivity takes place and the reaction of piperidinoallylamine can be controlled.PubDate: 2017-09-21T06:26:00.706198-05:DOI: 10.1002/ange.201708620

Authors:Matteo Ceppatelli; Demetrio Scelta, Roberto Bini, Maurizio Peruzzini, Kamil Dziubek, Adhara Baldassarre, Manuel Serrano-Ruiz, Andrew CairnsAbstract: Black Phosphorus was compressed at room T across the A17, A7 and simple-cubic phases up to 30 GPa, using a diamond anvil cell and He as pressure transmitting medium. Synchrotron X-ray diffraction showed the persistence of two previously unreported peaks related to the A7 structure in the pressure range of the simple-cubic one. The Rietveld refinement of the data demonstrates the occurrence of a two-step mechanism for the A7 to simple-cubic phase transition, indicating the existence of an intermediate pseudo simple-cubic structure. From a chemical point of view this study represents a deep insight on the mechanism of interlayer bond formation during the transformation from the layered A7 to the non-layered simple-cubic phase of Phosphorus, opening new perspectives for the design, synthesis and stabilization of Phosphorene based systems. As superconductivity is concerned, a new experimental evidence to explain the anomalous pressure behavior of Tc in Phosphorus below 30 GPa is provided.PubDate: 2017-09-21T06:20:29.774416-05:DOI: 10.1002/ange.201708368

Authors:Ye Zhang; Yiding Jiao, Lijun Lu, Lie Wang, Taiqiang Chen, Huisheng PengAbstract: To satisfy the rapid development of portable and wearable electronics, it is highly desired to make batteries with both high energy densities and flexibility. Although some progresses have been made in recent decades, the available batteries share critical problems of poor energy storage capacity and low flexibility. Herein, we have developed a silicon-oxygen battery fiber with high energy density and ultra-flexibility by designing a coaxial architecture with lithiated silicon/carbon nanotube hybrid fiber as inner anode, polymer gel as middle electrolyte and bare carbon nanotube sheet as outer cathode. It exhibited a high energy density of 512 Wh/kg and could effectively work after bending for 20,000 cycles. These battery fibers had been further woven into flexible textiles for a large-scale application.PubDate: 2017-09-21T05:21:03.720435-05:DOI: 10.1002/ange.201707840

Authors:Shavkat Mamatkulov; Christoph Allolio, Roland Netz, Douwe Jan BonthuisAbstract: The surface tension of the air-water interface increases upon the addition of inorganic salts, implying a negative surface excess of ionic species. Most acids, however, induce a decrease in surface tension, indicating a positive surface excess of hydrated protons. In combination with the apparent negative charge at pure air-water interfaces derived from electrokinetic experiments, this experimental fact has presented a source of intense debate since the mid 19th century. Here, we calculate surface tensions and ionic surface propensities at air-water interfaces from classical thermodynamically consistent molecular dynamics simulations. The surface tensions of NaOH, HCl and NaCl solutions show outstanding quantitative agreement with experiment. Of the studied ions, only H3O+ adsorbs to the air-water interface. The adsorption is explained by the deep potential well caused by the orientation of the H3O+ dipole in the interfacial electric field, which we comfirm using ab initio simulations.PubDate: 2017-09-21T01:21:31.28945-05:0DOI: 10.1002/ange.201707391

Authors:Hao Li; Tianyu Jiao, Liang Chen, Dong Yang, Xin Li, Guangcheng Wu, Pingmei Zeng, Ankun Zhou, Qi Yin, Yuanjiang Pan, Biao Wu, Xin Hong, Xueqian Kong, Vincent M Lynch, Jonathan L SesslerAbstract: Three tetrahedral organic cages have been obtained by condensing a triamino linker with a set of three ostensibly analogous triformyl precursors. In spite of the large number of imine bonds formed, the corresponding cages were obtained in exceptionally high yields. Both theory and experimental results demonstrate that, the presence of intramolecular CH***π interactions within all of the cage frameworks plays an important role in abeting the condensations and contributes to the near-quantitative synthetic yields. The three cages of this study exhibit high stability, both thermodynamically and kinetically. A variety of small neutral guest molecules with complementary sizes and geometries may be used as templates in the cage forming reactions. Among the guests that may be used in this way is white phosphorus (P4), whose inherent reactivity towards oxygen is almost fully attenuated when bound within one of the cages of this study.PubDate: 2017-09-20T12:21:26.777919-05:DOI: 10.1002/ange.201708246

Authors:Antonio M. Echavarren; Xiang Yin, Mauro MatoAbstract: The formal (3 + 2) cycloaddition between terminal allenes with aryl or styryl gold(I) carbenes generated by retro-Buchner reaction of 7-substituted 1,3,5-cycloheptatrienes leads to indenes and cyclopentadienes, respectively. These cycloadditions have been applied to the construction of the carbon skeleton of the cycloaurenones and the dysiherbols as well as to the total synthesis of ()-laurokamurene B.PubDate: 2017-09-20T12:21:17.189288-05:DOI: 10.1002/ange.201708947

Authors:Irina I. Ivanova; Yury G. Kolyagin, Ivan A. Kasyanov, Alexander V. Yakimov, Tatiana O. Bok, Dmitry N. ZarubinAbstract: Time-resolved 13C, 23Na, 27Al and 29Si MAS NMR has been applied in situ for monitoring the hydrothermal synthesis of zeolite BEA. Isotopic labelling with 29Si and 13C isotopes has been used to follow the fate of silicious species and structure directing agent ((13CH3-CH2)4NOH). Two mechanistic pathways, namely, solution mediated and solid-solid hydrogel rearrangement have been distinguished for two synthesis procedures studied. The mechanisms of structure directing behavior of TEA+ cations in two reaction pathways have been elucidated. The results show that multinuclear MAS NMR can serve as a superior tool for monitoring hydrothermal synthesis of various solids including zeolites, zeotypes, mesoporous materials, metal organic frameworks and etc. and for the design of novel outstanding materials for different applications.PubDate: 2017-09-20T07:21:48.282769-05:DOI: 10.1002/ange.201709039

Authors:Liangxin Fan; Jingjing Liu, Lu Bai, Yaoyu Wang, Xinjun LuanAbstract: A novel palladium-catalyzed three-component reaction of phenol-derived biaryls with N-benzoyloxyamines and norbornadiene (NBD) has been developed for the assembly of highly functionalized spiroindenes. This domino process was realized through NBD-assisted C-H amination and phenol dearomatization by forming one C-N bond and two C-C bonds in a single step. Preliminary studies indicated that asymmetric control of this transformation was feasible with chiral ligands. Moreover, the potential synthetic utility of this methodology was highlighted by a series of further transformations.PubDate: 2017-09-20T04:15:26.323673-05:DOI: 10.1002/ange.201708310

Authors:Shuang-Yan Lang; Yang Shi, Yu-Guo Guo, Rui Wen, Li-Jun WanAbstract: Lithium-sulfur (Li-S) batteries have been attracting wide attention due to their promising high specific capacity. Deep understanding of Li-S interfacial mechanism including the temperature (T) effect is increasingly required to meet the burgeoning demands for battery modification and systematic researches. Herein, interfacial behavior during discharge/charge is investigated at high temperature (HT) of 60 ̊C in electrolyte based on lithium bis(fluorosulfonyl) imide (LiFSI). By in situ atomic force microscopy (AFM), dynamic evolution of insoluble Li2S2 and Li2S is studied at the nanoscale. An in situ formed protective film can be directly monitored at 60 ̊C after Li2S nucleation, retarding side reactions and facilitating interfacial redox. The deep insight into the interfacial processes at HT discovers a direct evidence of the existence of the protective film and reveals its dynamic behaviors, providing a new avenue for electrolyte design and performance enhancement with a long span.PubDate: 2017-09-20T03:16:32.133522-05:DOI: 10.1002/ange.201706979

Authors:Carsten Schmuck; Hao Jiang, Xiao-Yu Hu, Stefanie Schlesiger, Mao Li, Elio Zellermann, Shirley KnauerAbstract: Herein, a novel cationic peptide gemini amphiphile containing diacetylene motifs (DA2P) is presented which self-assembles into novel tadpole- and bola-shaped nanostructures at low concentration and nanofibers at higher concentration, respectively. Interestingly, the DA2P assemblies can be polymerized to a fluorescent red phase but only during incubation with HeLa cells, most likely owing to the reorganization of the diacetylene chains of DA2P upon interaction with the cell membrane. The red-fluorescent polymerized DA2P assemblies can serve as a novel cell imaging probe. However, only vesicles, tadpole- and bola-shaped DA2P assemblies can be translocated into HeLa cells, while the nanofiber-like DA2P assemblies are trapped by the cell membranes and do not enter the cells. Hence, morphology dependent cell imaging is observed.PubDate: 2017-09-20T02:20:54.342761-05:DOI: 10.1002/ange.201708168

Authors:Zhiwei Huang; Samuel Miller, Binghui Ge, Mingtao Yan, Shashwat Anand, Tianmin Wu, Pengfei Nan, Yuanhu Zhu, Wei Zhuang, Jeffrey Snyder, Peng Jiang, Xinhe BaoAbstract: GeSe is a IV-VI semiconductor, like the excellent thermoelectric materials PbTe and SnSe. Orthorhombic GeSe has been predicted theoretically to have good thermoelectric performance but is difficult to dope experimentally. Like PbTe, rhombohedral GeTe has a multivalley band structure, which is ideal for thermoelectrics and also promotes the formation of Ge vacancies to provide enough carriers for electrical transport. Herein, we investigate the thermoelectric properties of GeSe alloyed with AgSbSe2, which stabilizes a new rhombohedral structure with higher symmetry that leads to a multivalley Fermi surface and a dramatic increase in carrier concentration. The zT of GeAg0.2Sb0.2Se1.4 reaches 0.86 at 710 K, which is 18 times higher than that of pristine GeSe and over four times higher than doped orthorhombic GeSe. Our results open a new avenue towards developing novel thermoelectric materials via crystal phase engineering using a strategy of entropy stabilization of high symmetry alloys.PubDate: 2017-09-20T01:15:58.037789-05:DOI: 10.1002/ange.201708134

Authors:Trevor Lohrey; Robert Bergman, John ArnoldAbstract: The reactivity of the oxo Re(V) β-diketiminate, OReCl2(BDI), with various cyclopentadienide (Cp) sources has been investigated. As a result, we have developed a route to a new class of terminal oxo complexes of Re(III) supported by olefin moieties of substituted cyclopentadienes. The success of this pathway is due to the electrophilic nature of the Cp ligand in the cation, [ORe(η5-Cp)(BDI)]+ (3+), which allows for nucleophilic attack by a variety of reagents under mild conditions. In contrast, tBuNC was found to attack at the oxo moiety to produce isocyanate by oxygen atom transfer.PubDate: 2017-09-19T20:46:28.478537-05:DOI: 10.1002/ange.201707957

Authors:Peter D Morse; Timothy F JamisonAbstract: We report a method for overcoming the low stability of nitroalkynes through the development of nitrated vinyl silyltriflate equivalents. Because of their instability, nitroalkynes have only rarely been utilized in synthesis. The reactivity of these silyltriflates, which are prepared in situ, is exemplified by dipolar cycloaddition reactions with nitrones to give highly substituted 4-nitro-4-isoxazolines in high yields. This approach has proven general for several different alkyl and aryl substituted alkynes. In order to minimize the accumulation of potentially hazardous reaction intermediates, we have also developed a continuous flow variant of this method that is capable of carrying out the entire reaction sequence in a good yield and a short residence time.PubDate: 2017-09-19T20:46:19.846433-05:DOI: 10.1002/ange.201706157

Authors:Satobhisha Mukherjee; Aleyda Garza-Sanchez, Adrian Tlahuext Aca, Frank GloriusAbstract: The development of new Hydrogen Atom Transfer (HAT) strategies within the framework of photoredox catalysis is highly appealing for its power to activate a desired C−H bond in the substrate leading to its selective functionalization. Reported here, is the first photoredox mediated Hydrogen Atom Transfer protocol for the efficient synthesis of ynones, ynamides and ynoates with high regio- and chemoselectivity by direct functionalization of sp2 C(O)-H bonds. The broad synthetic application of this method has been demonstrated by the selective functionalization of C(O)-H bonds within complex molecular scaffolds.PubDate: 2017-09-19T20:46:10.082784-05:DOI: 10.1002/ange.201708037

Authors:Kazuo Nagasawa; Minami Odagi, Yoshiharu YamamotoAbstract: The Amaryllidaceae alkaloid (+)-gracilamine (1), isolated from Galanthus gracilis, contains a characteristic pentacyclic ring system with seven consecutive stereogenic centers, including an all-carbon quaternary stereocenter. Herein, we report the first enantioselective total synthesis of (+)-gracilamine (1), featuring a diastereoselective phenolic coupling reaction followed by a regioselective intramolecular aza-Michael reaction to construct the ABCE ring system. The stereochemistry at C3a in 1 is controlled by the stereocenter at C9a, which was selectively generated (91% ee) by utilizing an organocatalytic enantioselective aza-Friedel-Crafts reaction developed by our group. This synthesis reveals that the absolute configuration of (+)-gracilamine (1) is (3aR, 4S, 5S, 6R, 7aS, 8R, 9aS).PubDate: 2017-09-19T20:45:58.081963-05:DOI: 10.1002/ange.201708575

Authors:Thomas Q Davies; Adrian Hall, Michael C. WillisAbstract: Sulfonimidamides are increasingly important molecules in medicinal chemistry and agrochemistry, but their preparation requires lengthy synthetic sequences, which has likely limited their use. We describe a one-pot de novo synthesis of sulfonimidamides from widely available organometallic reagents and amines. This convenient and efficient process uses a stable sulfinylamine reagent, N-sulfinyltritylamine (TrNSO), available in one step on 10 gram scale, as a linchpin. In contrast to classical approaches starting from thiols or their derivatives, our TrNSO-based approach facilitates the rapid assembly of the three reaction components into a variety of differentially substituted sulfonimidamides containing medicinally relevant moieties, including pyridines and indoles. Analogues of the sulfonamide-containing COX-2 inhibitor Celecoxib were prepared and evaluated.PubDate: 2017-09-19T20:45:46.142873-05:DOI: 10.1002/ange.201708590

Authors:kewei Wang; Liming Yang, Xi wang, Liping Guo, Guang Cheng, Chun Zhang, Shangbin Jin, Bien Tan, Andrew CooperAbstract: Covalent triazine frameworks (CTFs) are normally synthesized by ionothermal methods. The harsh synthetic conditions and associated limited structural diversity do not benefit for further development and practical large-scale synthesis of CTFs. Herein we report a new strategy to construct CTFs (CTF-HUSTs) via a polycondensation approach, which allows the synthesis of CTFs under mild conditions from a wide array of building blocks. Interestingly, these CTFs display a layered structure. The CTFs synthesized were also readily scaled up to gram quantities. The CTFs are potential candidates for separations, photocatalysis and for energy storage applications. In particular, CTF-HUSTs are found to be promising photocatalysts for sacrificial photocatalytic hydrogen evolution with a maximum rate of 2647 µmol h-1 g-1 under visible light. We also applied a pyrolyzed form of CTF-HUST-4 as an anode material in a sodium-ion battery achieving an excellent discharge capacity of 467 mAh g-1.PubDate: 2017-09-19T11:41:22.916554-05:DOI: 10.1002/ange.201708548

Authors:Xiuwen Chen; He Zhao, Chunlian Chen, Huanfeng Jiang, Min ZhangAbstract: By a hydrogen transfer-mediated activation mode for non-activated pyridyl nucleus, a general catalytic hydrogen transfer-mediated -functionalization of 1,8-naphthyridines is reported for the first time. Its -site selectively couples with the C8-site of various tetrahydroquinolines (THQs) to afford novel -functionalized tetrahydro 1,8-naphthyridines, a class of synthetically useful building blocks and potential candidates for the discovery of therapeutic and bio-active products. The utilization of THQs as inactive hydrogen donors (HDs) appears to be a key strategy to overcome the over-hydrogenation barrier and address the chemo-selectivity issue. The developed chemistry features operational simplicity, readily available catalyst and good functional tolerance, and offers a significant basis for further development of new protocols to directly transform or functionalize inert N-heterocycles.PubDate: 2017-09-19T10:46:19.888127-05:DOI: 10.1002/ange.201707702

Authors:David Yu-Kai ChenAbstract: Here we report asymmetric total syntheses of communesin F and a putative member of the communesin family of bis-aminal alkaloid natural products. The successful strategy featured the invention of an asymmetric organocatalytic reaction to unify two oxindole subunits, a Ti(OiPr)4-mediated dehydrative skeletal rearrangement, and a late-stage Pd(OAc)2-catalyzed directed CH-alkenylation reaction. Collectively, the synthetic technologies disclosed herein enabled the preparation of a late-stage polycyclic intermediate catered for the synthesis of both naturally occurring and designed communesins. More importantly, speculated and yet to be discovered member(s) of the communesin family can now be accessed to facilitate a better understanding of the communesin biosynthetic network.PubDate: 2017-09-19T10:45:52.466198-05:DOI: 10.1002/ange.201707806

Authors:Ahria Roushanbakhti; Yifan Liu, Paul Winship, Michael Tucker, Wasim Akhtar, Daryl Walter, Gail Wrigley, Timothy James DonohoeAbstract: Catalytic oxidative cyclisation reactions have been employed for the synthesis of the E and F rings of the complex natural product target pectenotoxin 4. The choice of metal catalyst (cobalt or osmium based) allowed for the formation of THF rings with either trans or cis stereoselectivity. Fragment union using a modified Julia reaction then enabled the synthesis of an advanced synthetic intermediate containing the EF and G rings of the target.PubDate: 2017-09-19T10:45:38.510384-05:DOI: 10.1002/ange.201708278

Authors:Li Wang; Yanhui Yi, Chunfei Wu, Hongchen Guo, Xin TuAbstract: The conversion of CO2 with CH4 into liquid fuels and chemicals in a single-step catalytic process that bypasses the production of syngas remains a challenge. In this study, liquid fuels and chemicals (e.g., acetic acid, methanol, ethanol, and formaldehyde) were synthesized in a one-step process from CO2 and CH4 at room temperature (30 °C) and atmospheric pressure for the first time by using a novel plasma reactor with a water electrode. The total selectivity to oxygenates was approximately 50–60 %, with acetic acid being the major component at 40.2 % selectivity, the highest value reported for acetic acid thus far. Interestingly, the direct plasma synthesis of acetic acid from CH4 and CO2 is an ideal reaction with 100 % atom economy, but it is almost impossible by thermal catalysis owing to the significant thermodynamic barrier. The combination of plasma and catalyst in this process shows great potential for manipulating the distribution of liquid chemical products in a given process.Elegante Abkürzung: Die Synthese von flüssigen Brennstoffen und Chemikalien (z. B. Essigsäure, Methanol, Ethanol und Formaldehyd) aus CO2 und CH4 gelang durch die Verwendung eines neuen Plasmareaktors mit einer Wasserelektrode erstmals in einem einstufigen Prozess bei Raumtemperatur (30 °C) und Atmosphärendruck. Die Selektivität für sauerstoffhaltige Verbindungen beträgt 50–60 %, mit Essigsäure als Hauptkomponente.PubDate: 2017-09-19T08:06:10.578202-05:DOI: 10.1002/ange.201707131

Authors:Holly J. Davis; Georgi R. Genov, Robert J. PhippsAbstract: Selective functionalization at the meta position of arenes remains a significant challenge. In this work, we demonstrate that a single anionic bipyridine ligand bearing a remote sulfonate group enables selective iridium-catalyzed borylation of a range of common amine-containing aromatic molecules at the arene meta position. We propose that this selectivity is the result of a key hydrogen bonding interaction between the substrate and catalyst. The scope of this meta-selective borylation is demonstrated on amides derived from benzylamines, phenethylamines and phenylpropylamines; amine-containing building blocks of great utility in many applications.Geschickte Positionierung: Ein Bipyridinligand, der eine entfernt stehende anionische Sulfonatgruppe trägt, dirigiert bei einer Reihe von amidischen Arenen die Iridium-katalysierte Borylierung an die meta-Position. Eine Wasserstoffbrückenwechselwirkung sorgt für die richtige Positionierung des Iridiumzentrums in der entscheidenden C-H-Aktivierung.PubDate: 2017-09-19T07:35:45.115058-05:DOI: 10.1002/ange.201708967

Authors:Leone Oliva; Patrizia Oliva, Nunzia Galdi, Claudio Pellecchia, Leonardo Sian, Alceo Macchioni, Cristiano ZuccacciaAbstract: The solution structure of AlMe2F and its reactivity with a prototypical ansa-metallocene have been investigated by advanced NMR techniques, in an attempt to indirectly shed some light on the "structure and working principles" of methylalumoxane (MAO) mixtures in olefin polymerization. In solution, AlMe2F leads to a complex equilibrium of oligomeric species, including a heterocubane [(Me2Al)4F4] tetramer, resembling the behavior of MAO. Such a complex mixture reacts with the prototypical ansa-zirconocene (ETH)ZrMe2 affording [(ETH)ZrMeδ+(μ-F)(AlMe2F)nAlMe3δ-] inner-sphere ion pairs through the successive insertions/deinsertion of AlMe2F units into the Zr…(μ-F) bond.PubDate: 2017-09-19T06:45:26.658313-05:DOI: 10.1002/ange.201707194

Authors:Daniel B. Werz; André Augustin, Peter G. Jones, Maximilian SensseAbstract: Lewis-acid-catalyzed reactions of 2-substituted cyclopropane 1,1-dicarboxylates with thioketones are described. Highly substituted tetrahydrothiophenes with two adjacent quaternary carbon atoms were obtained in a stereospecific manner under mild conditions and in high yield using AlCl3 as Lewis acid. Moreover, an intramolecular approach was successfully implemented to gain access to sulfur-bridged [n.2.1] bicyclic ring systems. Conversion of selenoketones, the heavier analogs, under similar conditions resulted in the formation of various tetrahydroselenophenes.PubDate: 2017-09-19T04:40:26.798022-05:DOI: 10.1002/ange.201708346

Authors:Lu Lin; Xiangbin Bai, Xinyi Ye, Xiaowei Zhao, Choon-Hong Tan, Zhiyong JiangAbstract: The first catalytic asymmetric photoreduction of 1,2-diketones and α-keto ketimines under visible light irradiation is reported. A transition-metal-free synergistic catalysis platform harnessing dicyanopyrazine-derived chromophore (DPZ) as the photoredox catalyst and a non-covalent chiral organocatalyst is effective for these transformations. With the flexible use of a chiral Brønsted acid or base in H+ transfer interchange to control the elusive enantioselective protonation, a variety of chiral α-hydroxy ketones and α-amino ketones were obtained with high yields and enantioselectivities.PubDate: 2017-09-19T03:40:46.840216-05:DOI: 10.1002/ange.201707899

Authors:Xiaofeng Ma; Joshua Farndon, Tom Young, Natalie Fey, John BowerAbstract: A C-N bond forming dearomatization protocol with broad scope is outlined. Specifically, bifunctional amino-reagents are used for sequential nucleophilic and electrophilic C-N bond formations, with the latter effecting the key dearomatization step. Using this approach, γ-arylated alcohols are converted to a wide range of differentially protected spirocyclic pyrrolidines in just two or three steps.PubDate: 2017-09-19T02:40:47.193008-05:DOI: 10.1002/ange.201708176

Authors:Jie Fu; Sara Elizabeth SkrabalakAbstract: There are few methods yielding oxynitride crystals with defined shape, yet shape-controlled crystals often render enhanced photoactivity. Here, single-crystalline SrTaO2N nanoplates and polyhedra are achieved selectively. Central to these synthetic advances is the crystallization pathways used, where single-crystalline SrTaO2N nanoplates form by topotactic nitridation of aerosol-prepared Sr2Ta2O7 nanoplates and SrTaO2N polyhedra form by flux-assisted nitridation of the nanoplates. Evaluation of these materials for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) showed improved performance for the SrTaO2N nanoplates, with a record apparent quantum efficiency (AQE) of 6.1% for OER compared to the polyhedra (AQE: 1.6%) and SrTaO2N polycrystals (AQE: 0.6%). The enhanced performance from the nanoplates arises from their morphology and lower defect density. These results highlight the importance of developing new synthetic routes to high quality oxynitrides.PubDate: 2017-09-18T20:45:53.338735-05:DOI: 10.1002/ange.201708645

Authors:Lei Zhang; Xiaoxiao Liu, Yuhai Dou, Binwei Zhang, Huiling Yang, Shixue Dou, Huakun Liu, Yunhui Huang, Xianluo HuAbstract: Architectural control of porous solids, such as porous carbon cages, has received considerable attention for versatile applications because of their attractive ability to interact with liquids and gases not only at the surface, but throughout the bulk. Here we report a scalable, facile spray-pyrolysis route to synthesize holey carbon microcages with mosquito-net-like shells. Using the surfaces of water droplets as the growth templates, styrene-butadiene rubber macromolecules are controllably cross-linked, and size-tunable holes on the carbon shells are generated. The as-formed carbon microcages encapsulating Si nanoparticles exhibit enhanced lithium-storage performances for lithium-ion batteries. The scalable, inexpensive synthesis of porous carbon microcages with controlled porosity and the demonstration of outstanding electrochemical properties are expected to extend their uses in energy storage, molecular sieves, catalysis, adsorbents, water/air filters and biomedical engineering.PubDate: 2017-09-18T10:40:25.900488-05:DOI: 10.1002/ange.201708732

Authors:Kevin Szkop; Andrew Jupp, Riccardo Suter, Hansjorg Gruetzmacher, Douglas Wade StephanAbstract: The reactions of the phosphaethynolate anion ([PCO]-) with a range of boranes were explored. BPh3 and [PCO]- form a dimeric anion featuring P-B bonds and is prone to dissociation at room temperature. The more Lewis acidic borane B(C6F5)3 yields a less symmetric dimer of [PCO]- with P-B and P-O bonds. Less sterically demanding HB(C6F5)2 and H2B(C6F5) boranes form a third isomer with [PCO]- with both boranes bound to the same phosphorus atom. Despite the unexpected thermodynamic preference for P-coordination, computational data illustrate that electronic and steric features impact the binding modes of the resulting dianionic dimers.PubDate: 2017-09-18T08:40:48.707893-05:DOI: 10.1002/ange.201708646

Authors:Qiang Sun; Bay V. Tran, Liangliang Cai, Honghong Ma, Xin Yu, Chunxue Yuan, Meike Stöhr, Wei XuPages: 12333 - 12337Abstract: The on-surface activation of carbon–halogen groups is an efficient route to produce radicals for constructing various hydrocarbons and carbon nanostructures. To date, the employed halide precursors have only one halogen attached to a carbon atom. It is thus of interest to study the effect of attaching more than one halogen atom to a carbon atom with the aim of producing multiple unpaired electrons. By introducing an alkenyl gem-dibromide, cumulene products were fabricated on a Au(111) surface by dehalogenative homocoupling reactions. The reaction products and pathways were unambiguously characterized by a combination of high-resolution scanning tunneling microscopy and non-contact atomic force microscopy measurements together with density functional calculations. This study further supplements the database of on-surface synthesis strategies and provides a facile manner for incorporation of more complicated carbon scaffolds into surface nanostructures.Auf der Oberfläche: Cumulene entstehen als Produkte der dehalogenierenden Homokupplung von Alkenyl-gem-dibromiden auf einer Au(111)-Oberfläche.PubDate: 2017-08-28T12:43:09.405066-05:DOI: 10.1002/ange.201706104

Authors:Shengwei Huo; Pengfei Duan, Tifeng Jiao, Qiuming Peng, Minghua LiuPages: 12342 - 12346Abstract: The design and fabrication of quantum dots (QDs) with circularly polarized luminescence (CPL) has been a great challenge in developing chiroptical materials. We herein propose an alternative to the use of chiral capping reagents on QDs for the fabrication of CPL-active QDs that is based on the supramolecular self-assembly of achiral QDs with chiral gelators. Full-color-tunable CPL-active QDs were obtained by simple mixing or gelation of a chiral gelator and achiral 3-mercaptopropionic acid capped QDs. In addition, the handedness of the CPL can be controlled by the supramolecular chirality of the gels. Moreover, QDs with circularly polarized white light emission were fabricated for the first time by tuning the blending ratio of colorful QDs in the gel. The chirality transfer in the co-assembly of the achiral QDs with the gelator and the spacer effect of the capping reagents on the QD surface are also discussed. This work provides new insight into the design of functional chiroptical materials.Zirkular polarisierte Lumineszenz (CPL) tritt bei gemischten Gelen mit Nanoröhrenstruktur auf, die aus achiralen Quantenpunkten (QDs) und einem chiralen Gelator erzeugt wurden. Vollfarbige und weiße CPLs wurden durch gezieltes Mischen mehrerer verschiedenfarbiger QDs mit dem chiralen Gelator erhalten.PubDate: 2017-08-24T03:46:41.151856-05:DOI: 10.1002/ange.201706308